The invention is directed to a quick release valve for a sprinkler head wherein a thermal responsive frangible element such as a glass bulb is used as the triggering element. The sprinkler head is coupled to a conduit which provides a pressurized fluid, such as water, for extinguishing a fire.
A sprinkler head wherein the compressive preload on the frangible element is reduced without substantially compromising the valve seal is disclosed in U.S. Pat. No. 4,167,974 (Job). The frangible element is mounted between the head body and a preloaded Belleville washer mounted on the valve seat. The underside of the washer is exposed to fluid at the valve flow passage so that the fluid impinges directly on the washer. This results in a uniform distribution of fluid pressure over the bottom surface of the preloaded washer whereby the washer will flex to accommodate fluid pressures experienced during normal operation.
The problem solved by the present invention is that of reducing the compressive preload required to protect the frangible element during normal operation by as much as 60%. As a result, lightweight and thinner walled frangible elements may be employed so as to provide a quicker response or triggering action (breakage) at the selected threshold temperature, all without compromising the frangible element or the valve seal.